Convoluted cone wheel

ABSTRACT

A non-pneumatic convoluted cone wheel having a hub section and a resilient section that has a ground-engaging rim at its peripheral outer edge portion to which a tire tread can be provided for the ground engaging rim including an internal element to vary the rate of the wheel with deformation under load which is turnable for changing stiffness with deformation of the resilient section.

This is a division, of application Ser. No. 745,533 filed June 17, 1985and now U.S. Pat. No. 4,705,087.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

This invention relates to vehicle wheels and, more particularly, tolight-weight non-pneumatic cone wheels.

2. Discussion Of The Prior Art

For well over a half a century, automotive vehicles have conventionallyrun on a two component assembly comprising a pneumatic tire mounted on aspoked or solid wheel. The drawbacks of these two-component assembliesare well-known and include, among other disadvantages, their cost,weight, and the susceptibility of the pneumatic tire component toblow-outs and punctures. In their search for a solution to theseproblems, the prior art has investigated a number of design approaches.Among the more promising are designs in which the wheel itself issufficiently resilient to allow the pneumatic tire to be eliminatedwithout sacrifice in acceptable life and riding and handling properties.An example of a resilient non-pneumatic solid one-component wheel in theprior art is the elastic conoidal wheel which is the subject of U.S.Pat. No. 3,698,461 invented by the inventor of the present invention andassigned to a common assignee. That prior art design had a hub and aresilient conoidally shaped body extending from the hub to aground-engaging rim which served as the running surface of the wheel. Inaddition to a wheel of conoidal design, a convoluted cone wheel was alsodisclosed. A further teaching of a convoluted cone wheel in the priorart is the design disclosed by W. J. Hampshire in U.S. Pat. No.4,350,196. Hampshire discloses a wheel assembly which has a hub and anintegrally formed rim portion having a more-or-less S-shaped radialcross-sectional configuration. These prior art designs provide apractical resilient wheel that allows the pneumatic tire normallyrequired to be eliminated without an appreciable sacrifice in ridingcomfort or vehicle handling characteristics. However, these prior artresilient wheels have a spring rate when deflected under load influencedby their required overload strength properties and thus advantage cannotbe taken of the improvement possible with a resilient wheel which has arate that can be varied with deflection under load. Non-pneumaticresilient wheels typically suffer from having an inadequate footprintfor good highway handling properties if the structure must also endurethe expected 3-g dynamic loading with ample fatigue life. In addition,the prior art does not provide means by which the spring rate of aconoidal wheel can be changed such that the operating characteristics ofthe wheel can be tailored to meet various requirements. The compromiseof having adequate strength for dynamic overload conditions and adequatesuppleness at 1-g for good handling has not been satisfactorily solvedin the prior art.

Accordingly, it is an object of the invention to provide a vehiclenon-pneumatic wheel structure having the service, ride, and handlingperformance characteristics similar to a conventional pneumatic tire andwheel assembly at loads up through the design load of the wheelstructure.

A further object of the invention is to decouple the loads imposed byimpact dynamics from a more supple resilient structure tailored fordesirable handling properties at a nominal 1-g loading.

It is another object of the invention to provide a non-pneumatic wheelstructure having mechanical functions and safety characteristics thatare superior to those of a conventional pneumatic tire and wheelassembly at loads above the design load of a pneumatic tire and wheelassembly.

A yet further object of the invention is to provide a resilientnon-pneumatic convoluted cone wheel capable of large deformation whoserate with deflection under load can be tailored to meet specific designobjectives.

Yet another object of the invention is to provide a variable-rateresilient non-pneumatic convoluted cone wheel which is of unitarylightweight high-strength construction which can be designed to simulatethe appearance of a conventional wheel and pneumatic tire assembly.

A further object of the invention is to provide a variable-rateresilient non-pneumatic convoluted cone wheel which has the mechanicalfunctions and riding characteristics of a conventional wheel andpneumatic tire assembly but which has a lower rolling resistance.

Another object of the invention is to provide a resilient nonpneumaticwheel which is simple in design; economical to manufacture, operate, andservice; and capable of withstanding static, fatigue, and impact loadscompatible with expected service requirements.

Other objects and advantages of the present invention will becomeapparent to those skilled in the art from the description to follow whenread in conjunction with the drawings appended hereto.

SUMMARY OF THE INVENTION

The above-mentioned objectives are achieved by the present inventionwhich provides a resilient non-pneumatic convoluted cone wheel having ahub section for receiving an axle and a resilient conoidal wheel bodysection forming a radially outward continuation of the hub section, theresilient section has a ground-engaging rim at its peripheral outer edgeportion. If desired, a tire tread can be provided for theground-engaging rim portion. Means are also provided to vary the springrate of the wheel with deformation under load. The resilient section ofthe wheel is annularly dished in the axial direction to form a coaxialhollow semi-conoid of relatively thin cross-section having a circularradially and axially curving portion forming a continuation of the hubsection and a circular reversedly curving substantially arcuateperipheral portion forming a continuation of the circular radially andaxially curving portion. The spring rate of the resilient conoidalsection of the wheel can be changed by means of a series of radial slotslocated coaxially around the resilient section in approximately thevertex region of the semi-conoid area thereof or at is radially inwardregion at approximately the juncture of the semi-conoid area with thehub section. Alternately, the resilient wheel body section can be madein two coaxial pieces with a radially inside piece and a radiallyoutside piece whose edges abut in the vertex region. A series ofelongated spring clips bridging the abutting edges and having the clipends fastened to the opposite coaxial pieces can be provided to changethe rate. In a further embodiment, opposing flanges can be formed in theabutting edges of the two pieces of the resilient conoidal section andthey can be fastened together with a resilient gasket interposedtherebetween to change the spring rate. A further means for varying thespring rate of the resilient conoidal section of the wheel is aresilient bump stop. The bump stop has a circular configuration (whenviewed from the side) coaxial with but with a smaller radially outerdiameter than the normal undeflected diameter of the rim of theresilient conoidal section. The outer peripheral edge of the bump stopterminates in a location which intercepts the path of the insidereversedly curved surface of the resilient conoidal section during thedeformation thereof under conditions of increased load. When theresilient conoidal section deforms to a degree that brings it intocontact with the resilient bump stop, the bump stop comes into play toretard further deformation, thus changing the spring rate of the wheeland utilizing two spring systems in series; the primiary conoidalsection, and the bump stop.

DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings the forms which are presently preferred; however, it should beunderstood that the invention is not necessarily limited to the precisearrangements and instrumentalities here shown.

FIG. 1 is a diametric section of a wheel embodying the presentinvention;

FIG. 2 is a fragmentary diametric section of an embodiment of the wheelof FIG. 1 whose ground-engaging rim portion is provided with a tread;

FIG. 3 is a diametric section of yet another embodiment of the wheel ofthe present invention;

FIG. 3a is an enlarged fragmentary cross-sectional view of the wheel ofFIG. 3 showing the construction in greater detail;

FIG. 4 is a diametric section of a further embodiment of the wheel ofthe present invention;

FIG. 5 is a fragmentary diametric section of the resilient annularsection of still another embodiment of the wheel of the invention;

FIG. 6 is a side elevational view of a yet further embodiment of thewheel of the invention;

FIG. 7 is a diametric section taken along line 7--7 of the wheel of FIG.6;

FIG. 8 is a fragmentary elevational view taken along line 8--8 of thewheel of FIG. 6;

FIG. 9 is a diametric section of another embodiment of the wheel of theinvention;

FIG. 10 is a fragmentary elevational view taken along line 10--10 of thewheel of FIG. 9; and

FIG. 11 is a fragmentary diametric section of an alternate designlocation for the spring clips of the FIG. 9 embodiment of the wheel ofthe present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference now to the drawings, FIG. 1 shows an embodiment 10 of thenon-pneumatic convoluted cone wheel of the invention. Wheel 10 has a hubsection 12, an integral web section 14 which forms a radial continuationof the hub section, a resilient annular toroidal wheel body section 16extending radially outwardly from the web section, and a resilient bumpstop 18 of circular configuration. Hub section 12 is suitably configuredfor mounting wheel 10 on a conventional vehicular wheel mount (notshown) and may have a centrally located through hole 20 for receiving anaxle and a pattern of holes 22 located around central hole 20 forreceiving the threaded fasteners (not shown) used to secure wheel 10 tothe vehicle wheel mount. In the FIG. 1 embodiment, bump stop 18, whichcan be suitably fastened to hub section 12 as by riveting (not shown),is provided with an arrangement of through holes 24 and 26 matchingholes 20 and 22 respectively of the hub section. Bump stop 18, whichpreferably is located on the wheel on the side adjacent the vehicle, hasa radially outward peripheral edge 28 which is smaller in diameter thanthe wheel rim 36, is provided with means imparting resiliency to thebump stop. In the FIG. 1 embodiment, the peripheral portion 30 of thebump stop has an axially inwardly curving arcuate configuration thatimparts resiliency to the bump stop. Thus, arcuate edge portion 30 has aconcave section 32 facing the vehicle and a convex section 34 facing theinside surface of toroidal section 16. It will be appreciated that wellknown means other than that shown in FIG. 1 can be employed to impartthe required resiliency to the bump stop.

In a convoluted cone wheel, the required resiliency in operation that isnormally supplied by the pneumatic tire in the prior art is provided bya resilient conoidal wheel body section. In the present invention, thefunction is served by resilient annular toroidal wheel body section 16which can be considered to extend radially outwardly from about diameterA of the wheel to its rim 36. Toridal section 16 has a circular radiallyand axially outwardly curving portion 38 forming a continuation of websection 14 and a circular reveresedly radially and axially inwardlycurving portion 40. Toroidal section 16 thus has a concave insideportion 42 and a convex outside portion 44.

In the wheel of this invention, the design of the toroidal wheel bodysection 16 preferably is one in which the sum of the axial dimensions B& C of the section is approximately equal to twice the section depth D.(See FIG. 1) If the geometry is varied to one having a relationship lessthan two, the wheel stiffness is significantly increased such that itbehaves more like a rigid wheel. A larger ratio will reduce thestiffness of the wheel but adverse lateral strains may begin to beintroduced into the surface contact area of the wheel at approximatelyplus or minus 45° (viewed from the front elevation of the wheel) to thecenterline of the footprint. It will be appreciated that, at thediscretion of the designer, the diametric cross-sectional profile of thebump stop also can be essentially similar to that of the resilienttoroidal section i.e., the sum of the axial dimensions of the bump stopcan be approximately equal to twice the section depth thereof.

To enhance the wear and traction of wheel 10, wearing surface means suchas a tread 46 (see FIG. 2) can be provided on the rim 48 area of thewheel. A solid tread, which may be made of rubber or other suitableelastometric substance, preferably is employed, but a design containingone or more openings or cavities or even a low-profile pneumaticbelt-type tire can be used. The cross-section of the solid treadsuitably has an unloaded concave shape designed so that the center bandportion will lie flat on the road surface as the band portion passesunder the wheel axle during each revolution. This results in a good loaddistribution and even wear during highway operation. The side bands ofthe tread, which do not make contact until off-road conditions areencountered, can have aggressive treads or cleats for increased tractionin weak soil conditions. A certain amount of lateral scuffing will beencountered with a conoidal wheel. To reduce energy loss and excessiveheating at highway speeds, the tread should be designed to accommodateas much as this scuffing motion as possible. To comply with theselateral motions elastically, the center band portion of the tread canincorporate deep circumferential grooves. Radial or transverse groovealso can be provided to minimize the hoopwise stiffening effect of thetread as it rounds the leading and trailing "corners" of the deformedwheel in operation (In the interest of clarity, the tread 46 shown inFIG. 2 is not shown in FIG. 1. Although a tread is not shown in thedrawings of the other embodiments of the invention, it will beappreciated that a tread can be provided as desired at the discretion ofthe designer.)

In operation when mounted on a vehicle, the rim 48 region of theresilient toroidal section 16 of the wheel beneath and on either side ofthe wheel axle will deform and flatten under load. Preferably the wheelis designed such that when its rim deforms approximately 10% under aload, the inside surface 50 of the wheel rim region will deform, asindicated in broken lines in FIG. 1, such that it is brought up againstthe peripheral edge 28 portion of the bump stop 18. Further deformationof the wheel thus will be resisted not only by the stored energy in thetoroidal section 16 but also by the stored energy of the bump stop 18.This changes the spring rate of the wheel under deformation such thatthe wheel has dual rates with deformation, with one spring rate duringinitial deformation and a second, stiffer, rate when the bump stop comesinto play.

Non-pneumatic convolute cone wheels are fatigue sensitive. Designs toaccept high-"g" impact loads severely limit the footprint size in normaloperation. A softer spring-rate elastic structure would permit the wheelto overcome the footprint problem, but difficulties with the wheelover-deflecting under high-g loads normally prohibits this designapproach. However, in my invention, possible problems withover-deformation are avoided by the resilient bump stop which limits thedeformation undergone by the wheel. It is thus possible to provide adesign in which the deformation at 1.5-g is limited to a valuedetermined by the handling properties of the wheel. In my invention, thenon-pneumatic convoluted cone wheel can be designed to accept impactloads above 1.5-g and a 1-g static load to provide an adequate footprintfor handling. All dynamic bottoming loads are attenuated by the bumpstop. The design is not penalized by measures that would have to betaken normally to accommodate high-g loads, thus it has reduced weightand improved handling performance and reduced ride harshness.

A further embodiment 110 of the non-pneumatic convoluted cone wheel ofthe invention is shown in FIG. 3. Wheel 110 has a hub section 112, aresilient annular toroidal wheel body section 116 extending radiallyoutwardly from the hub section, and a resilient bump stop 118 of annularconfiguration similar to that of toroidal section 116. A low-frictionelastomeric ring 119 can be provided around the edge portion 128 toavoid possible chafing between the bump stop and the resilient section116. Hub section 112 is suitably configured for mounting wheel 110 on aconventional vehicular wheel mount such as a brake drum 111. A centrallylocated through hole 120 for receiving the end 113 of the vehicle axleand a pattern of holes 122 for receiving the threaded wheel studs 123 ofthe vehicle wheel mount can be provided to enable the wheel to bemounted. In this embodiment, the hub section 112 has an axially inwardlydisposed annular, peripheral, cylindrical flange 152 for receiving thevehicle brake rotor or drum 111. In this design, the radially innermostcylindrical edge portions 154 and 156 of toroidal section 116 and bumpstop 118 respectively are fastened to the outer periphery of flange 152by a peripheral arrangement of suitable fasteners such as bolts 158. Inthe arrangement, toroidal section edge portion 154 is sandwiched betweenflange 152 and bump stop edge portion 156 to provide the requisiteclamp-up forces for the assembly. As indicated in FIG. 3a, edge portion154 of resilient section 116 can be suitably thickened as at 155 toproperly distribute the loads thereon. Flush-head countersunk bolts 158can be used in this embodiment to fasten the foregoing together whileproviding the proper clearance for the vehicle's brake drum 111.

In FIG. 3, wheel 110 is shown with a bump stop 118 having aconfiguration in diametrical cross section substantially duplicating thediametrical cross section of toroidal wheel body section 116. It will beappreciated, however, that a reduction in the section depth E of thebump stop as indicated in the broken-line configurations 118¹ and 118²will have the effect of increasing the spring rate to thereby influencethe step function of the arrangement accordingly. This increase inspring rate with a reduction in the section depth of the bump stop will,of course, apply with respect to the bump stops in the other embodimentsof my invention.

The convoluted cone wheels of this invention can be fabricated out awide range of suitable metallic and non-metallic materials. For example,in the FIG. 1 embodiment, the various components of wheel 10 can bemolded out of a composite such as fiberglass reinforced epoxy resin. Ifa metal is used in the wheel, cryoformed stainless steel or aheat-treated low-alloy high-strength steel would be leading candidatematerials for the resilient elements of the wheel. Generally, because ofcost and other considerations, a fiberglass reinforced epoxy resin willbe selected. However, in an installation such as in FIG. 3 where thewheel is to be mounted on the brake drum of the vehicle, the wheel inoperation will be subjected to an intense heat input from the brake.Therefore, when, for example, a composite material is used in theresilient section 116 of the wheel 110 of FIG. 3, the wheel hub 112 ismade of metal to avoid a thermal degradation of strength of theresilient material. With a metal hub 112, the heat transfer to theresilient section 116 of the wheel is in a temperature range that can betolerated by the generally used composite materials. Thus, it is notnecessary to employ a more expensive high-temperature grade plasticmaterial in the design of resilient section 116.

Wheel 110 of the FIG. 3 embodiment has substantially similar operatingcharacteristics to wheel 10 of the FIG. 1 embodiment and differstherefrom essentially in the means provided for mounting the wheel on avehicle.

Yet another embodiment 210 of the convoluted cone wheel of the inventionis shown in FIG. 4. As in wheel 110 of the FIG. 3 embodiment wheel 210has a hub section 212, a resilient annular toroidal wheel body section216 extending radially outwardly from the hub section, and a resilientbump stop 218 of circular configuration. As in the FIG. 3 wheel 110,suitable means are provided in the hub section to enable wheel 210 to bemounted on a vehicle and similar flange means are used to install thetoroidal section 216 and bump stop 218 on hub section 212. Substantiallythe only difference between the FIGS. 3 and 4 embodiments is that thetoroidal section 216 of wheel 210 is constructed in two semi-hemisphericsegments 260 and 262. Segment 260 has a circular radially and axiallyoutwardly curving configuration which is fastened to and extends fromhub 212. Segment 262 has a circular reversedly radially and axiallyinwardly curving configuration. Each segment has an axially extendingflange 264 and 266 respectively around the adjoining peripheral edges268 and 270 at the vertex 272 of the toroidal section. An arrangement ofsuitable fasteners such as bolts 274 are used peripherally to securesegments 260 and 262 together.

Wheel 210 has substantially the same dynamic response to static andimpact loads as the wheel 110 embodied in FIG. 3 and its operatingcharacteristics are equivalent thereto. Also, as in the previousembodiments, the resilient bump stop 218 gives the wheel a dual-modulusspring rate.

FIG. 5 illustrates an alternative design for the wheel 210 embodied inFIG. 4. The wheel 310 of FIG. 5 has a hub section (not shown) and atwo-piece resilient toroidal wheel body section 316 comprising two semihemispheric segments 360 and 362. Segment 360 has a circular radiallyand axially outwardly curving configuration which is fastened to andextends from the wheel hub section. Segment 362 has a circularreversedly radially and axially inwardly curving configuration. Eachsegment has an axially extending flange 364 and 366 respectively whichare fastened together as by means of suitable fasteners such as bolts374 which preferably are of a type that will accept or minimize bendingloads imposed thereon by flexure of the flange. However, unlike wheel210 embodied in FIG. 4 in which the segments are fastened together withthe facing surfaces of the flanges in intimate contact, a rubber orelastomeric gasket 376 is interposed between the facing surfaces offlanges 364 and 366 around the entire circumference thereof. To permitthe necessary freedom of movement for the bolts during flexture of theflanges, rubber or elastomer sleeves or grommets 378 and 380 areprovided for each bolt. Gasket 376 has a spring rate different from thatof resilient segments 360 and 362 such that it acts as a flexible jointto vary the stiffness of the cone wheel. By properly selecting anelastomer to obtain one with a desired resiliency, a designer can tailorthe stiffness of the wheel to meet various requirements.

It is also feasible to tailor the spring rate of the wheel of myinvention by means of radial slots such as those illustrated in wheel410 shown in FIGS. 6-8. Wheel 410 has a hub section 412, a resilientannular toroidal wheel body section 416 which forms a continuation ofand extends radially outwardly from the hub section, and a bump stop418. Bump stop 418 has a circular configuration in plan view with acentral aperture that is provided with an axially inwardly extendingcylindrical flange 456 which is a tight fit over the axially inwardlyextending cylindrical flange 452 of the hub section. The two flanges aresecurely fastened together as by bonding or by means of suitablefasteners such as flush-head rivets 458. It will be seen that the wheelas described to this point, with the exception of minor variations inthe hub area thereof, is substantially identical to the wheel 10 ofFIG. 1. As in the other wheels of this invention, the necessaryresilience required for the efficient functioning of the wheel isprovided by the toroidal section 416. In wheel 410, the spring rate andfootprint characteristics which are highly important to the handlingproperties of the wheel are tailored by slotting the resilient toroidalwheel body section 416 with an annular arrangement of through slots 450of various lengths, widths, and spacing. As shown in FIGS. 6 and 7, theslots can be arranged in an annular pattern at the point of greatestcurvature in the curved profile of resilient section 416 such as at thevertex 470 of the section. Typically, the slots 450 can be about 0.060in. wide, about 3 in. long, and they can be spaced about 1 in. apart.The width, length, and spacing of slots 450 are determined empiricallyfor the desired elastic deformation characteristics of the wheel.Preferably, each slot 450 has the general shape shown in FIG. 8 in whicheach end of each slot is relieved with an aperture 462 and 464 having adiameter greater than the slot width such that a stress build-up in theslotted area of section 416 of the wheel during deformation is relieved.Alternately, instead of a pattern of slots at vertex area 470, anannular pattern of slots can be provided for varying the stiffness ofthe wheel at any other transition point in the curvature of the profileof section 416 as, for example, at annular area 460 adjacent hub section412. If the requirements so dictate, of course, the wheel can be slottedat both areas 470 and 460 such that the stiffness of the wheel isreduced accordingly.

In wheel 510 embodied in FIGS. 9 and 10 the spring rate of the wheel istailored by spring clip means 550. Wheel 510 has a hub section 512, anda resilient annular toroidal wheel body section 516 which forms acontinuation of and extends radially outwardly from the hub sectionResilient toroidal section 516 of wheel 510 is constructed in twosemi-hemispheric segments 560 and 562. Segment 560 has a circularradially and axially outwardly curving configuration which extends fromhub 512. Segment 562 has a circular reversedly radially and axiallyinwardly curving configuration. Segments 56O and 562 are fastenedsecurely together with a slight clearance gap 566 therebetween by springclips 550 arranged around the adjoining edges 565 and 567 of thesegments. As is evident from FIG. 9, the edges of the segmentspreferably are joined together at a location corresponding to the vertex570 of the toroidal section 516. As best shown in FIG. 10, each springclip 550 can have a more-or-less hour-glass shaped configuration in planview with widened portions 569 and 571 at each end and a necked-inmidsection 573 which serves as a cantilever spring means between thesegments. End 569 of the spring clip is fastened to segment 560 as bybonding or by suitable fasteners such as rivets 568 and end 571 of theclip is similarly fastened to segment 562. Clips 550 are located on theinside concave surface 572 of the resilient toroidal section but theycan be located as indicated in FIG. 11 on the outside, convex surface574 at the discretion of the designer. The designer can select anappropriate stiffness for the spring clips and for the resilienttoroidal section to produce a desired spring rate profile for the wheelunder deformation. As is the case with slotting the wheel to vary itsspring rate, the size, spacing, and material of the clips will bedetermined by the desired elastic deformation. A 0.040 or 0.050 in.thick stainless steel spring clip which is one-in. wide at its widestdimension and spaced one-in. apart has been found suitable in practice.

It will be appreciated that design features of one embodiment of theinvention such as the slots 450 of the wheel 410 embodiment can beincorporated, where appropriate, in other embodiments of the invention.Further, should it be advantageous to do so in certain applications,various embodiments of the wheels of the invention can be operatedwithout bump stops. It will be understood, also, that the wheel can bemounted, if desired, with the annular concave side thereof facingoutwardly away from the vehicle.

Although shown and described in what are believed to be the mostpractical and preferred embodiments, it is apparent that departures fromthe specific methods and designs described and shown will suggestthemselves to those skilled in the art and may be made without departingfrom the spirit and scope of the invention. I, therefore, do not wish torestrict myself to the particular constructions described andillustrated, but desire to avail myself of all modifications that mayfall within the scope of the appended claims.

Having thus described by invention, what I claim is:
 1. A non-pneumaticconvoluted cone wheel comprising:a hub section for receiving an axle; aresilient torodial wheel body section extending radially outwardly fromsaid hub section and having a rim at its peripheral edge portion distalfrom said hub section, said rim having an inside surface portion and anoutside ground-engaging portion, said toroidal section being formed intwo coaxial pieces with a radially inside circular radially and axiallyoutwardly curving portion and a radially outside circular reversedlyradially and axially curving portion such that said toroidal section hasan annular, concave inside surface and an annular convex outsidesurface, means for joining the contiguous edges of said coaxial pieces;and means automatically operative in all conditions of operation forchanging the spring rate upon a certain amount of deformation of saidtoroidal section.
 2. The convoluted cone wheel defined in claim 1 wherein the means for changing the spring rate is a resilient bump stop. 3.The convoluted cone wheel defined in claim 2 wherein the resilient bumpstop has a circular configuration in plan view coaxial with said toridalsection and having a smaller diameter than the normal undeformeddiameter of the rim of the toroidal section, the outer peripheralportion edge of said bump stop terminating radially in a positionintercepting the path of the inside surface portion of said toroidalsection during the deformation thereof under conditions of increasedload.
 4. The convoluted cone wheel defined in claim 3 wherein theresilient bump stop has a spring rate under deformation greater thanthat of the toroidal section whereby when the inside surface of saidtoroidal section contacts said bump stop, further deformation of saidwheel is resisted by the combined stiffness of both the bump stop andthe toroidal section such that an overstressing of said toroidal sectionunder load is prevented.
 5. The convoluted cone wheel defined in claim 4wherein the radially outward peripheral region of the bump stop has aconoidal configuration having a cross-sectional profile substantiallysimilar to that of the toroidal section of said wheel and the convexsurface thereof faces the inside surface of said toroidal section. 6.The convoluted cone wheel according to claim 5 in which the hub sectionhas a substantially planar vertical disk portion which has a peripheralaxially inwardly extending cylindrical flange and the radially insideperipheries of the resilient toroidal section and the bump stop have acylindrical edge portion coaxial with said flange and fitted thereonwith the cylindrical portion of said toroidal section interposed betweensaid cylindrical portion of said bump stop and said hub flange with aperipheral arrangement of fasteners through said flange and saidcylindrical edge portions for fastening said edge portions to saidflange with the requisite clamping forces on the assembly.
 7. Theconvoluted cone wheel according to claim 6 in which the cylindrical edgeportion of said resilient toroidal section is thickened to properlydistribute the loads thereon.
 8. The convoluted cone wheel according toclaim 6 in which said wheel is mounted on the brake drum wheel mountingof a vehicle.
 9. The convoluted cone wheel according to claim 8 in whichthe hub section is metallic and the resilient toroidal section is madeof a composite material, said hub section being provided with anoperating clearance between it and the brake drum such that heattherefrom into said hub section in operation is substantially a radiantheat transfer phenomenon whereby a heat input into said toroidal sectionof a magnitude sufficient to cause thermal degradation of the compositematerial thereof is avoided.
 10. The convoluted cone wheel defined inclaim 1 wherein the means for joining the contiguous edges of thecoaxial pieces is a circumferential arrangement of spring clips, thespring clips each having one of their ends fastened on one of thecoaxial pieces and the other of their ends fastened on the other coaxialpiece, the portion of said spring clips intermediate said fastened endforming a cantilever spring, whereby the action of said cantileverspring portions of said clips during deformation of the wheel under loadchanges the spring rate of the resilient toroidal section.
 11. Theconvoluted cone wheel defined in claim 10 wherein the spring clips eachare substantially rectangular strips of resilient sheet material. 12.The convoluted cone wheel defined in claim 2 wherein the means forjoining the contiguous edges of the coaxial pieces is an axiallyoutwardly projecting integral flange provided along both of saidcontiguous edges and wherein said flanges are fastened together tosecure said coaxial pieces together for operation.
 13. The convolutedcone wheel defined in claim 1 wherein the means for joining contiguousedges of the coaxial pieces is an axially outwardly projecting integralflange provided along both of said contiguous edges, said flanges beingfastened together to secure said coaxial pieces together for operation,and wherein a peripheral elastometric gasket is interposed between themating surfaces of said flanges whereby the resilience of said gasketchanges the spring rate with deformation of said wheel.
 14. Theconvoluted cone wheel according to claim 1 in which the sum of the axialdimensions in width of the circular radially and axially outwardlycurving portion and the circular reversedly radially and axiallyinwardly curving portion of the resilient annular body section isapproximately twice the section radial depth of said resilient annularbody section.
 15. The convoluted cone wheel according to claim 1 inwhich said wheel has an annular web section interposed between the hubsection and the resilient annular toroidal section.
 16. The convolutedcone wheel according to claim 15 in which the annular web section isresilient.
 17. The convoluted cone wheel according to claim 15, in whichthe annular web section is integral with the hub section and theresilient annular toroidal section.